Wow! Congratulations!
MSx is a much smaller programs than HBS and seems to have an older crowd that is much more committed and connected. I have recently connected one of the GMAT Club users with an MSx VC alum (former Sloan program) and despite the fact that he graduated 15 years ago, they responded right away and clearly good enough impression to drop INSEAD from one's radar. I feel the MSx program is more for successful non-MBA types that consider the program in some ways a finishing touch to their career rather than a start/beginning of their new track. Does that make sense? I don't think anyone has gone to Stanford and felt they missed out on anything - it is not #2, it is rather an alternative to HBS. Kind of like the folks who choose Lexus instead of BMW or Mercedes that are too cliche. However, note that MSx wont' connect you with alums before you are committed and matriculating, unlike many other schools and programs.
I don't think you can go wrong with HBS really. It is #1 for a reason.
The main choices are:
1 year vs. 2 (are you looking for a new career path that needs an internship and 2 years)?
The second choice is the age group - are you looking for peers/older/more accomplished/experienced people with families and kids or the rising stars? There are pros and cons to both, though HBS will have a good number of more mature quieter people too. HBS students are some of the nicest and humble people I have ever met.
I would add the program size matters - one is much smaller than the other and finally the networks. I would guess (I have no hard facts) that MSx is mostly west coast-based alum network but maybe I am off.... I also feel MSx has a fair share of VC presence in its alum ranks.... and while smaller, it is probably pretty tight. You can consider reaching out to karroty here:
https://gmatclub.com/forum/insead-vs-st ... 45636.html